﻿// -----------------------------------------------------------------------
// <copyright file="TypeSystem.cs" company="Spardo, LLC">
// Copyright (c) 2011 SPardo, LLC
//
// Permission is hereby granted, free of charge, to any person obtaining a 
// copy of this software and associated documentation files (the "Software"), 
// to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included 
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
// </copyright>
// -----------------------------------------------------------------------

namespace BBYOpen.Linq.Common
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Runtime.Serialization;

    /// <summary>
    /// TODO: Update summary.
    /// </summary>
    internal static class TypeSystem
    {
        internal static Type GetElementType(Type type)
        {
            Type ienum = FindIEnumerable(type);
            if (ienum == null) return type;
            return ienum.GetGenericArguments()[0];
        }

        internal static string GetDataContractName(Type type)
        {
            var output = type.Name.ToLower();

            var attrs = type.GetCustomAttributes(typeof(DataContractAttribute), true);
            var member = attrs.First();

            if (member != null)
                output = ((DataContractAttribute)member).Name;

            return output;
        }

        internal static string GetElementDataContractName(Type type)
        {
            var genericType = GetElementType(type);
            return GetDataContractName(genericType);
        }
        
        private static Type FindIEnumerable(Type type)
        {
            if (type == null || type == typeof(string))
                return null;

            if (type.IsArray)
                return typeof(IEnumerable<>).MakeGenericType(type.GetElementType());

            if (type.IsGenericType)
            {
                foreach (Type arg in type.GetGenericArguments())
                {
                    Type ienum = typeof(IEnumerable<>).MakeGenericType(arg);
                    if (ienum.IsAssignableFrom(type))
                    {
                        return ienum;
                    }
                }
            }

            Type[] ifaces = type.GetInterfaces();
            if (ifaces != null && ifaces.Length > 0)
            {
                foreach (Type iface in ifaces)
                {
                    Type ienum = FindIEnumerable(iface);
                    if (ienum != null) return ienum;
                }
            }

            if (type.BaseType != null && type.BaseType != typeof(object))
            {
                return FindIEnumerable(type.BaseType);
            }

            return null;
        }
    }
}
